See here for the instruction sheet, and see below for maintenance schedule 

Spark Plug - Malibu LT4 Engine Application

The E100219 is a high-quality iridium spark plug designed for reliable performance and longevity, making it an excellent choice for Malibu boat engines, specifically the LT4 Monsoon engine.

Why Choose These for Malibu LT4 Engines:

• Optimal Performance: The fine-wire iridium electrode provides consistent, efficient ignition, which is crucial for the high-performance demands of the LT4 engine.

• Durability: Designed to withstand high temperatures and pressures typical of these powerful marine engines.

• Marine Suitability: Coated to resist corrosion and fouling, essential in marine environments where moisture and salt exposure are common.

• Extended Service Life: This reduces maintenance with a lifespan often exceeding 100,000 miles in automotive equivalents.

Compatible Malibu Boat Models:

• Boats equipped with Malibu LT4 Monsoon V8 Engine

Installation Tips:

• Follow Malibu’s torque specifications and use anti-seize on threads to prevent sticking.

• Check the gap before installation (typically pre-gapped for standard use).